1. Field of the Invention
The present invention relates generally to pressurized water supply systems and, more particularly, to an air volume control valve apparatus for use with a water system pressure tank.
2. Discussion of the Prior Art
In rural areas wells are frequently the only source of water readily available to local residents. In order to supply this water to a home or business at a generally constant pressure, it is known to employ a pressurized water supply system.
This known type of supply system includes a holding tank that is charged to a predetermined pressure with air so that water stored in the tank may be drawn at will by opening a faucet downstream of the tank, the water being delivered under pressure to the faucet. The system also includes a pump that is actuated when the pressure in the tank drops below a predetermined minimum pressure. Once actuated, the pump operates until the pressure in the tank reaches a predetermined maximum pressure.
Typically, conventional pressurized water supply systems include some means for recharging the air within the tank in order to maintain the desired pressure. This means compensates for the loss of air into the water, and replenishes the air in the tank during each cycle of operation of the pump.
However, the air charging means in conventional systems delivers slightly more air to the tank than is necessary to maintain the desired volume, resulting in a build-up of the volume which displaces the water level in the tank. If the volume of air in the tank becomes too excessive, the water level is pushed beneath the outlet opening of the tank, allowing the air to enter the downstream plumbing. This creates a nuisance and adversely affects the quality of the system.
A conventional solution to this problem is to provide an air volume control valve within the tank for releasing excess air that is introduced by the recharging means of the system. The air volume control valve includes a tube extending into the tank and presenting a restricted orifice through which the tube is in communication with the tank, and a float positioned beneath the orifice for vertical linear translation between a lower flow-permitting position exposing the orifice and a raised flow-preventing position blocking the orifice.
The control valve is positioned within the tank at a predetermined height such that the float is held in the raised position as long as the water level is above the minimum desired level. However, as the water drops below this minimum level, the float drops under the force of gravity toward the flow-permitting position so that air is released from the tank.
A problem experienced with this conventional type of air volume control valve is that the float has a tendency to remain drawn against the orifice in the tube since the float is not heavy enough to overcome the pressure differential between the tank and the ambient conditions within the tube. Although it is possible to combat this problem by reducing the size of the orifice relative to the float, such a reduction in the orifice size creates a new problem in that sediment and other solids plug the orifice and prevent proper venting of air from the tank.